Wobble in the Standard Model
Prediction is very difficult, especially if it’s about the future—Niels Bohr
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| Boston Globe “Uncertainty” source |
Lisa Randall is a professor of theoretical physics at Harvard. Her research has touched on many of the basic questions of modern physics: supersymmetry, Standard Model observables, cosmological inflation, baryogenesis, grand unified theories, and general relativity. She has also written popular books about her work and science in general. Thus she has a handle on aspects of science that overlap my expertise—not to mention those of her sister Dana Randall, whom I have known as a colleague for many years.
Today, Ken and I thought we would talk about recent developments in particle physics, and their connection to two topics dear to us.
Randall’s most recent popular book is Dark Matter and the Dinosaurs. The idea she advances is that the periodic extinctions in Earth’s history may have been caused when the solar system passes through a plane of dark matter within our galaxy. But dark matter and also dark energy have come under increasing recent doubt, even from their original formulator. Maybe Niels Bohr’s quote should also say:
Prediction is very difficult, especially if it’s about the past.
Randall’s previous book, Knocking on Heaven’s Door, is most relevant to this post. The 1973 Bob Dylan song title it pinches describes the feeling of doing frontier physical science. Insofar as her own work is mostly theoretical, much of it connects to feelings we have in computer science—especially complexity lower bounds where the door mostly feels slammed shut.
But the book is also about the practice of experimental science—not only how to gather knowledge but when and how we can have confidence in it. Its long middle part is titled, “Machines, Measurements, and Probability.” All three elements are foremost in considering a new development that involves two measurements taken 20 years apart.
Muons
Last Tuesday’s New York Times highlighted a potential discovery in particle physics. It was in their Tuesday science section.
The result is an experimental discovery that could show that the current model of matter is wrong.
“This is our Mars rover landing moment,” said Chris Polly, a physicist at the Fermi National Accelerator Laboratory, or Fermilab, in Batavia, Ill., who has been working toward this finding for most of his career.
Indeed. It is a Mars landing moment. They both involved many people, lots of exotic machinery, lots of money, many years. Say three billion dollars or so for Mars. Say nearly the same amount for muons—the annual budget for Fermilab is over one half billion dollars. It was certainly enough to reassemble and upgrade a huge accelerator ring that was first used at Brookhaven National Lab on Long Island in 2001:
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The study used the muon to probe the Standard Model of physics. Muons are useful because they are charged like an electron, which helps control them in an accelerator. Yet their mass is roughly 207 times larger than an electron. The same charge helps control their motion and the large mass makes collisions more interesting. As Polly stated in Natalie Wolchover’s story for Quanta:
“[I]f you’re looking for particles that could explain the missing mass of the universe—dark matter—or you’re looking for [supersymmetry], that’s where the muon has a unique role.”
Theory and Jealousy
Computer science theory is so different from high end physics. We are closer to the type of research that Randall does. We involve few people, no exotic machinery, and small amounts of money. Maybe the closest attribute we have to high-end research is we also take years and years.
Perhaps we are also jealous of high-end physics. Not just for money, but for the ability of particle physicists to get announcements into the New York Times. Polly said the following about the ending day of the muon experiment two decades ago:
When we revealed the results, people from all over the world flew in to visit the lab. These experiments take decades to build and analyze, so you don’t get to go to very many of these events. We did a little “Drumroll, please” and then had the postdoc managing the spreadsheet hit the button to show it on the projector. Lo and behold, you could see that there was still a three-sigma discrepancy!
At the time he was a graduate assistant assigned to machinery for measuring particle energies. He had fixed a problem where someone had touched a component with bare hands and thereby ruined its sheathing. All such problems were meant to be ironed-out by the drum-roll event. But all this raises two further interesting issues that connect the muon results with issues we think about in computer science. Let’s look at them next.
Three to Four Sigma
In an experimental science one must be aware that results are not exact. They are samples from some random process. Flip a coin 10 times in a row. If they all come up heads what does that mean? Could be the coin is fair but this happens about one time in a thousand. Or the coin is biased. Or something else.
Flip a muon many times. That is sample some muon experiment. The outcome is from a random process. Some of it comes from properties of the natural processes themselves and others from incidentals of the measurement apparatus. How do we decide if the experiment means what we think it does?
The theory developed by Carl Gauss and others before and after to delineate the normal distribution was largely prompted by analysis of measurement errors to begin with. This yields the “rule of three,” about the percentage of values that naturally lie within an interval estimate in a normal distribution: 68%, 95%, and 99.7% of the values lie within one, two, and three standard deviations of the mean, respectively.
The question is, how to assess cases where the measurement result is well outside these intervals—when can we conclude it is more than a deviation by natural chance? In social sciences a result is “significant” provided it lies outside two-sigma. In particle physics, there is a convention of a five-sigma effect (99.99994% confidence) being required to qualify as a discovery. No Nobel prize for less.
The situation with the muons has an extra factor of repeated measurements—but there have been only two measurements so far:
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The blue line in the left figure is the original Brookhaven measurement; the red is the new one. There is also theoretical uncertainty in the calculation of the Standard Model prediction, and that combines with the measurement error bars to give the sigma baseline. The chart at right normalizes the deviation to parts per billion—the measurements need to be incredibly fine. This scale appears to be about 25% under the current 
Although the new Fermilab result by itself deviates slightly less from the Standard Model, it corroborates the earlier measurement. It is not fully independent from it, but the combination is enough to raise the current claimed deviation to about 
The social significance of 
The
The second factor we draw attention to concerns the human “hoping” directly.
Blinding
In any experimental science one must also be aware that people are not unbiased. Scientists have much invested in the outcome of their experiments. Think jobs, tenure even, funding, and more. So a big physics experiment like the muon one must be careful. They follow standard practice to perform blinded data analysis.
This surprised me. This blinding is a crypto-type protocol, which is something we computer scientists study. The muon team performed a protocol that protected against cheating. Here is how they did it:
In this case, the master clock that keeps track of the muons’ wobble had been set to a rate unknown to the researchers. The figure was sealed in envelopes that were locked in the offices at Fermilab and the University of Washington in Seattle.
In a ceremony on Feb. 25 that was recorded on video and watched around the world on Zoom, Dr. Polly opened the Fermilab envelope and David Hertzog from the University of Washington opened the Seattle envelope. The number inside was entered into a spreadsheet, providing a key to all the data, and the result popped out to a chorus of wows.
“That really led to a really exciting moment, because nobody on the collaboration knew the answer until the same moment,” said Saskia Charity, a Fermilab postdoctoral fellow who has been working remotely from Liverpool, England, during the pandemic.
This mechanism for blinding suggests possible crypto questions. They hid the master clock rate. Can this be modeled as one of our crypto problems? Can we prove some security bounds? If they claim that hiding the rate protects against cheating then they should be able to make this claim precise. The discovery of gravitational waves used a blind injection scheme tailored for that experiment. How can this be generalized?
Open Problems
We have discussed two aspects that involve soft numbers rather than hard machines and hard-shelled particles. Perhaps they are interesting new problems for us? What do you think?
I don’t think it’s true to say that there is any randomness whatsoever at all in the Universe. What there may be, is the powerful and convincing illusion of randomness. I think the answer to the question “Do we live in the best Universe possible?” is yes, we do. Then the question becomes, given the seeming random nature of reality, chaos, entropy etc, how is it possible that we have free will and yet everything is simultaneously predetermined to the nth degrees ranging from sub-molecular to supra-astronomical? It’s simple really – the Universe is time-bounded (constrained, or limited if you like), whereas outside of the Universe, time has no reality. The Bible – in its truest and most original form, basically explains that the soul is the body – the body is animated by the spirit – so soul equals body (inanimate earth/dust) plus spirit (animate living consciousness). Hence why computers will never be intelligent – how could they be, when they don’t contain spirit and never will. Schrodinger’s Cat was an excellent metaphor not for physics and quantum weirdness per se, but actually for life itself. Because what (99.9999999% of) people so spectacularly fail to understand and realise, is that we as humans, living our life are really dead and alive at the same time. But only external to time – that is the nature of our ephemeral life here on Earth. (From our perspective we perceive our own being through our consciousness, which is a part of being – we don’t know we’re dead, we only know we’re alive). A force exists outside the material world that is not just beyond materiality, but beyond spirituality also – it transcends everything, because that thing has the property of “being”. But having the property doesn’t really put it very well – but rather, it doesn’t just have the property of being as such, it is being itself. But this means that it can’t un-be, because then it wouldn’t be being – therefore what happened was, it created the Cosmos as a way for us humans to eventually un-be, having lived a life of being. In order to do this, we are bound by time, but the strange thing is, we perceive time as a tangible thing that passes and we notice as we age and things change, etc. But really, this is an illusion, because outside material existence there is no time. Therefore, it’s not right to say we live for x amount of years or whatever, because the truth is, one second here on Earth has no direct corollary outside of physicality. In other words, one Earth second, or billions of Earth years, are all the same to what lies outside the physical universe – “it makes no bones” to it, as the idiom goes. In other words, what it all really boils down to then, is that in, let’s pick something quite arbitrarily – as that is the ultimate nature of time – arbitrariness – the interval between a human heart beat, the entire Universe was created, played itself out into its eventual destination, and was transformed anew at the end of time. The point being really, that time had a beginning; it will have an end. But because the spirit part of us is outside of time, and the material part of us is within time, then a dichotomy exists – we see death and decay all around us; because that is the illusion of time – but guess what – illusions aren’t real, and eventually the illusion we call temporal life – because it’s only temporary (and too secular to last in that degraded form), will pass away, to be replaced by something permanent. I like the analogy of sleeping for death, because it’s the best one we have. Every time you sleep for (most of us) 6 to 8 hours a night, your spirit is living in that place outside of time; the ONLY difference being, is that when you are dead in the time-limited world, your spirit has nowhere to return to in the physical plane. But then think of your life like a grand cosmic video tape, but only with basic functionality as you live it. The key point to remember is, there is no time outside of the physical world. So at some point in the future, once eternity kicks in, your spirit gets re-inserted into your soul, and instead of the day counter being set for a maximum of 43830 (give or take about 10 days perhaps), as it was in your original existence here on Earth, then maybe you get an upgrade. I ask you, who wouldn’t want to do meaningful work here on Earth, and get paid in time? Probably only the foolishly wealthy in terms of illusory worldly riches would object to the institution of such a system – because there is only one currency with which time can ever be bought, and that’s morality. It’s also a fact that has been covered up by the sick, perverted and benighted spiritual and moral paupers of this world, but that the highest echelons of creativity go hand in hand with morality, spirituality – and in the sense that a hefty proportion of fundamental truths are mathematical ones, then they are fruits of the intellect as well. But a healthy intellect will without exception, never result from a diseased morality – and any apparent contradiction to this is just that – an appearance – ersatz, bogus, fallacious and sham. I can’t help but thinking that for this very reason then, in some ultimate and wonderful sense pertaining to the eternal, physics is a complete waste of time, because it can change and is malleable – whereas the truths of mathematics are immutable, ineffable, timeless and transcendent.
Thanks for reading. And remember – heaven has always been, and will (almost) forever (but not quite) remain just a heartbeat away.
“Perhaps we are also jealous of high-end physics. Not just for money, but for the ability of particle physicists to get announcements into the New York Times.”
Perhaps the current work on the muon will lead to a genuine discovery. In the meantime, I think it’s better to work in fields like CS or math that still make genuine progress, rather than in a field like fundamental physics which has replaced scientific progress by hype and unsupported speculation.
A $5\sigma$ model of a working apple computer would not be marketable unless it is a particle which computes in physics. $5\sigma$ is a manufacturing metric and physics should be at a higher standard given the complexities of experiments are exponentially increasing every generation. So within the timeline you are in tenure track the world has moved on except tenure positions which are staying there for two generations following $5\sigma$ metric.
Re: Knocking on Heaven’s Door
A more poignant theme song might be this —
“Perhaps we are also jealous of high-end physics. Not just for money, but for the ability of particle physicists to get announcements into the New York Times.”
Perhaps the current work on the muon will lead to an important discovery. In the meantime I think it’s better to work in fields like CS or math where genuine progress is still being made, rather than in a field like fundamental physics where scientific progress has been almost completely replaced by hype and unsupported speculation.